The influence of the quality of the aluminum in the aluminum-plastic lid on the sealing quality

1. The influence of the quality of aluminum in the aluminum-plastic cover on the sealing quality
Whether it is an all-aluminum lid or an aluminum-plastic composite cap, or whether it is a tear-off cap or not, the basis of the oral liquid aluminum-plastic cap is an aluminum cap. The aluminum cap of the oral liquid is made of industrial pure aluminum or rust-proof aluminum, which meets the requirements, and other grades of aluminum are also used. Among them, the industrial pure aluminum has high plasticity, low hardness and large delay rate, and the aluminum cap produced by it is easy to roll when sealing, so the lock mouth of the seal is smooth and smooth, not easy to wrinkle, and the fit between the cap and the bottle mouth is good. At the same time, the hardness HV value of the aluminum cover has standards for each manufacturer, and too low and too high can not meet the requirements of good sealing.

In addition, the wall thickness of the aluminum cover also has a great impact on the sealing quality and pass rate, the general aluminum cover wall thickness standard is 0.2mm, and the variation range is 0.18-0.22mm. However, at present, the actual wall thickness of domestic aluminum covers is 0.14-0.26mm, and thinner aluminum covers (especially those with larger diameters) are prone to wrinkles when sealed. In order to achieve a better sealing effect, the fitting gap between the aluminum cap and the bottle mouth should be slightly smaller, and the height of the aluminum cap should be correspondingly shorter.

2. The influence of the fit between the aluminum cap and the bottle mouth on the sealing quality.
The fit between the aluminum-plastic cap and the bottle mouth has a great influence on the sealing quality, including the radial fit tolerance and the axial (height direction) fit tolerance of the aluminum-plastic cap and the bottle mouth. In the radial fit tolerance group, including the inner diameter of the aluminum-plastic cap D1 and the outer diameter of the bottle mouth D2, the fitting gap is generally 0.3mm-0.4mm. When the gap is too small, the white moving cover process will appear "wearing the cover" is not correct and "wearing the cover" is not on; When the gap is too large, it is easy to fall off the cap, the shape of the lock is not round, the sealing is not tight, and it is easy to loosen in the capping process. In addition, for the aluminum-plastic cover with thick wall thickness (0.2--0.26mm), a larger fitting gap can be appropriately selected.